Author Topic: Artemis 1 Discussion Thread  (Read 229724 times)

Offline mn

  • Full Member
  • ****
  • Posts: 728
  • United States
  • Liked: 594
  • Likes Given: 213
Re: Artemis 1 Discussion Thread
« Reply #1180 on: 09/22/2022 07:59 pm »
NASA-STD-8719.25 "Range Flight Safety Requirements" requires that there be FTS telemetry on battery voltage and temperature.  I had the impression that this telemetry was not being produced continuously but only when the system was armed.  And I don't know when it's armed.  https://standards.nasa.gov/sites/default/files/standards/NASA/Baseline/1/nasa-std-871925_baseline_with_change_1.pdf

(Again basing on what I read elsewhere in NSF, most likely earlier in this thread, but the search in NSF totally fails me)

SLS needs to be powered up for the FTS system to power up and transmit telemetry, but they don't need a WDR to power it up.

Offline Pheogh

  • Full Member
  • ****
  • Posts: 967
  • Liked: 111
  • Likes Given: 28
Re: Artemis 1 Discussion Thread
« Reply #1181 on: 09/22/2022 08:00 pm »
Why is there so little conversation about the weather in here? They must have to make some kind of decision about rolling back or not like yesterday. Best case scenario is a 6-day roll? As of now that brings us to the 28th? Hydrogen fix or Range at this point are kind a moot correct?

Offline ccdengr

  • Full Member
  • ****
  • Posts: 506
  • Liked: 364
  • Likes Given: 58
Re: Artemis 1 Discussion Thread
« Reply #1182 on: 09/22/2022 08:03 pm »
NASA-STD-8719.25 "Range Flight Safety Requirements" requires that there be FTS telemetry on battery voltage and temperature.  I had the impression that this telemetry was not being produced continuously but only when the system was armed...
Since the launch abort motor is inert, I'm not sure when the system is armed for Artemis 1.
Sorry, I shouldn't have said "armed".  I presume that the FTS has not been sitting there running and transmitting this whole time but could be somehow switched or commanded into a lower-power state, but maybe that's not even true.

Offline Orbiter

  • Senior Member
  • *****
  • Posts: 2887
  • Florida
  • Liked: 1376
  • Likes Given: 1333
Re: Artemis 1 Discussion Thread
« Reply #1183 on: 09/22/2022 08:26 pm »
12z model run prediction for 98L.

Unfortunately, it's looking like when this develops, it's going to develop fast. From first advisory to actual impacts may be less than 4 days. The TVCN represents the model consensus.

As always, still plenty of time for this to change.

credit: https://www.tropicaltidbits.com/storminfo/#98L
« Last Edit: 09/22/2022 08:41 pm by Orbiter »
Astronomer & launch photographer

Offline Bennett

  • Photographer
  • Full Member
  • *
  • Posts: 102
  • North Carolina
  • Liked: 330
  • Likes Given: 409
Re: Artemis 1 Discussion Thread
« Reply #1184 on: 09/22/2022 08:32 pm »
Levi has a video with great information on the storms. Short version is it really depends on where the low will form in the next couple of days. https://www.tropicaltidbits.com

Online rdale

  • Assistant to the Chief Meteorologist
  • Senior Member
  • *****
  • Posts: 10256
  • Lansing MI
  • Liked: 1116
  • Likes Given: 132
Re: Artemis 1 Discussion Thread
« Reply #1185 on: 09/22/2022 08:33 pm »
Models are indicating the hurricane potential might be around the 29th. If that does pan out, it's hard for me to see them pressing into a 27th launch attempt due to the possibility of a scrub & recycle that day.

The system isn't even a depression, and the value of models at this stage in a potential storm's formation is close to zero.

Not quite zero - but close to it.

You'll notice by the ensembles that it could be anywhere from Brownsville Texas to Columbia South Carolina next week. That's a clue :)


Offline Zed_Noir

  • Senior Member
  • *****
  • Posts: 4258
  • Canada
  • Liked: 1267
  • Likes Given: 1132
Re: Artemis 1 Discussion Thread
« Reply #1186 on: 09/22/2022 10:01 pm »
Models are indicating the hurricane potential might be around the 29th. If that does pan out, it's hard for me to see them pressing into a 27th launch attempt due to the possibility of a scrub & recycle that day.

The system isn't even a depression, and the value of models at this stage in a potential storm's formation is close to zero.

Not quite zero - but close to it.
<snip>
Think we will have a better idea where 98L is heading after it go pass Jamaica. 

Offline Pheogh

  • Full Member
  • ****
  • Posts: 967
  • Liked: 111
  • Likes Given: 28
Re: Artemis 1 Discussion Thread
« Reply #1187 on: 09/22/2022 11:39 pm »
Can we get a poll going in here before the presser tmrw on whether they will make an attempt for the 27th?

Offline PahTo

  • Full Member
  • ****
  • Posts: 1684
  • Port Angeles
  • Liked: 259
  • Likes Given: 1106
Re: Artemis 1 Discussion Thread
« Reply #1188 on: 09/23/2022 12:44 am »
Can we get a poll going in here before the presser tmrw on whether they will make an attempt for the 27th?

Mark me down for December...

Offline sdsds

  • Senior Member
  • *****
  • Posts: 6436
  • “With peace and hope for all mankind.”
  • Seattle
  • Liked: 1390
  • Likes Given: 1313
Re: Artemis 1 Discussion Thread
« Reply #1189 on: 09/23/2022 01:16 am »
Today's test leaves me dubious that by relying on the current QD hardware and seals the program will ever meet its launch countdown goals.

Well done analyzing and interpreting the full test data set

NASA engineers and managers had access to the full data sets of each of the prior attempts to load hydrogen. Based on analysis of that data they designed a test procedure. They wanted to determine if they could get through a count without needing contingency stop-flow procedures when purge can hydrogen levels exceeded limits. That was not the result during this attempt. They did meet their test objectives, and obtained a pretty definite negative test result.

So based on all the prior data and analysis their model of the physics didn't accurately predict the behavior of the system. Having conducted this test they have more data. Now they can do more analysis. I sincerely wish them luck on their next tanking attempt using this design. But I also hope they have the courage to redesign, with an emphasis on getting a system where their physics model matches observed behavior. 
« Last Edit: 09/23/2022 01:22 am by sdsds »
— 𝐬𝐝𝐒𝐝𝐬 —

Offline DanClemmensen

  • Senior Member
  • *****
  • Posts: 2469
  • California
  • Liked: 1903
  • Likes Given: 735
Re: Artemis 1 Discussion Thread
« Reply #1190 on: 09/23/2022 01:47 am »
Can we get a poll going in here before the presser tmrw on whether they will make an attempt for the 27th?

Mark me down for December...
December is their last chance. The window is Dec 9-22. The SRB stacking limit runs out on 6 Jan 2023, and the next window is Jan 7-22 2023. the stack limit has already been extended in several increments from the original one year to the current two years. A further extension cannot be justified on technical grounds, and analytically the failure probability of an SRB seal increases as the seal ages.

A case can be made that NASA should launch in Q1 2023 if they cannot launch earlier on the grounds that the cost of a de-stack/restack is so high that it's better to risk an SRB failure. After all, Artemis I is uncrewed, the SRBs might not fail, and even if they do fail NASA might still learn something. Destack/restack will cost a year (made-up number) while failure will also cost a year (made-up number).

Offline Hog

  • Senior Member
  • *****
  • Posts: 2536
  • Woodstock
  • Liked: 1416
  • Likes Given: 5012
Re: Artemis 1 Discussion Thread
« Reply #1191 on: 09/23/2022 01:58 am »
Can we get a poll going in here before the presser tmrw on whether they will make an attempt for the 27th?

Mark me down for December...
December is their last chance. The window is Dec 9-22. The SRB stacking limit runs out on 6 Jan 2023, and the next window is Jan 7-22 2023. the stack limit has already been extended in several increments from the original one year to the current two years. A further extension cannot be justified on technical grounds, and analytically the failure probability of an SRB seal increases as the seal ages.

A case can be made that NASA should launch in Q1 2023 if they cannot launch earlier on the grounds that the cost of a de-stack/restack is so high that it's better to risk an SRB failure. After all, Artemis I is uncrewed, the SRBs might not fail, and even if they do fail NASA might still learn something. Destack/restack will cost a year (made-up number) while failure will also cost a year (made-up number).
Plus the FTS would require a rollback at minimum for December.   Rollback for FTS, to the pad for launch, then rollback for ML destack and solid motor swap.  That's not a pretty scenario.

Paul

Offline kdhilliard

  • Full Member
  • ****
  • Posts: 981
  • Kirk
  • Tanstaa, FL
  • Liked: 1374
  • Likes Given: 3395
Re: Artemis 1 Discussion Thread
« Reply #1192 on: 09/23/2022 02:06 am »
... The SRB stacking limit runs out on 6 Jan 2023, and the next window is Jan 7-22 2023. the stack limit has already been extended in several increments from the original one year to the current two years. ...

No.  I've seen that 2 year limit stated here a number of times, but it is not correct.  The original 1 year stacking limit did run out in January 2022 and was reportedly extended by six months.  A lot of people think it was extended another six, but NASA has never stated that.*  In one of the recent media briefings (sorry -- I don't recall which) they stated that they did not have a fixed hard limit, but were instead continuing to monitor and analyze the associated risks -- though at some point a limit would be reached.  (Or something like that -- anyone recall better?)


* If NASA did state a second six month extension then I missed it, and in the spirit of Cunningham's Law I would love to see a reference (or even just be told otherwise based on a firm recollection).
« Last Edit: 09/23/2022 06:13 am by kdhilliard »

Offline hektor

  • Senior Member
  • *****
  • Posts: 2380
  • Liked: 964
  • Likes Given: 38

Offline sdsds

  • Senior Member
  • *****
  • Posts: 6436
  • “With peace and hope for all mankind.”
  • Seattle
  • Liked: 1390
  • Likes Given: 1313
Re: Artemis 1 Discussion Thread
« Reply #1194 on: 09/23/2022 09:16 am »
tbf 2 years will give the engineers the chance to redesign any faulty equipment. its not like they must use the same spec for every launch. they will hopefully find a way to mitigate and fix this...

I like that thinking! Is there any evidence in what NASA officials have said publicly that they see it that way too? Or does what they say sound more like they are (again) normalizing ways to work around an evident problem, thinking that if it doesn't bite them too badly this time it isn't likely to do so in the future, convincing the public the system as currently designed is really just fine? Because that second way of thinking about things has been a part of NASA culture for quite some time. Quoting Feynman's appendix to the Rogers Commission report: "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." https://history.nasa.gov/rogersrep/v2appf.htm

— 𝐬𝐝𝐒𝐝𝐬 —

Offline kdhilliard

  • Full Member
  • ****
  • Posts: 981
  • Kirk
  • Tanstaa, FL
  • Liked: 1374
  • Likes Given: 3395
Re: Artemis 1 Discussion Thread
« Reply #1195 on: 09/23/2022 09:45 am »
Why is there so little conversation about the weather in here? They must have to make some kind of decision about rolling back or not like yesterday. Best case scenario is a 6-day roll? As of now that brings us to the 28th? Hydrogen fix or Range at this point are kind a moot correct?

From 52:50 of Monday's Artemis I Pre-Demonstration Test Media Teleconference:
Quote
Marcia Smith, SpacePolicyOnline.com: Would you remind us how much time it takes you to get it back to safety in the VAB and then back out to the pad if it's a hurricane as opposed to something like replacing the FTS?

Jeremy Parsons, Exploration Ground Systems deputy manager: We're watching all storms very closely.  Our team receives weather briefings first thing every morning.  Basically, in the event of a hurricane we would need to make a decision about three days out to roll back to the Vehicle Assembly Building.  That's why we're keeping an eye on everything at this point.  It differs depending on how far into the pad flow we are.  If we had just rolled out it would be a different timeline than where we are now.  Where we're at today it would take three days.

Online FutureSpaceTourist

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 27633
  • UK
    • Plan 28
  • Liked: 51387
  • Likes Given: 21957
Re: Artemis 1 Discussion Thread
« Reply #1196 on: 09/23/2022 10:25 am »
https://twitter.com/sciguyspace/status/1573254042867875840

Quote
Weather continues to be a concern for NASA and Artemis I with the newly formed Tropical Depression Nine. Earliest arrival of Tropical Storm-force winds over Kennedy Space Center is now Monday night or Tuesday morning.

Even if a storm doesn’t directly hit the Cape, weather could obviously still be a no go for launch. Monday night is only 3.5 days away and they need 3 days for rollback. So I assume they’ll make a decision this morning. Personally I don’t see they can take the risk? (I’m assuming risk of hitting is at least 5%. If it’s actually 0.5% then maybe that’s acceptable?)

Offline TorenAltair

  • Full Member
  • ****
  • Posts: 501
  • Germany
  • Liked: 572
  • Likes Given: 109
Re: Artemis 1 Discussion Thread
« Reply #1197 on: 09/23/2022 11:00 am »
« Last Edit: 09/23/2022 11:01 am by TorenAltair »

Online rdale

  • Assistant to the Chief Meteorologist
  • Senior Member
  • *****
  • Posts: 10256
  • Lansing MI
  • Liked: 1116
  • Likes Given: 132
Re: Artemis 1 Discussion Thread
« Reply #1198 on: 09/23/2022 11:19 am »
Maybe this was missed earlier - but any forecast after day 3 on the NHC map has little value at this point. It could be anywhere at any strength on the 27th, but probably not centered near KSC given the current forecast. This system literally just formed and has had zero (0) aircraft recon missions in it yet.

For those saying it has to be rolled back due to tropical storm force winds - that's 39mph. It gets stronger winds than that in every thunderstorm that has hit the pad since it rolled out.

And the NHC maps are not "models" - those are created by humans. You will never find a model in a NHC graphic.

Offline Perchlorate

  • Full Member
  • **
  • Posts: 234
  • 2 miles from the site of the first successful powered flight.
  • Liked: 488
  • Likes Given: 603
Re: Artemis 1 Discussion Thread
« Reply #1199 on: 09/23/2022 11:20 am »
https://twitter.com/sciguyspace/status/1573254042867875840

Quote
Weather continues to be a concern for NASA and Artemis I with the newly formed Tropical Depression Nine. Earliest arrival of Tropical Storm-force winds over Kennedy Space Center is now Monday night or Tuesday morning.

Even if a storm doesn’t directly hit the Cape, weather could obviously still be a no go for launch. Monday night is only 3.5 days away and they need 3 days for rollback. So I assume they’ll make a decision this morning. Personally I don’t see they can take the risk? (I’m assuming risk of hitting is at least 5%. If it’s actually 0.5% then maybe that’s acceptable?)
I believe they have already made the decision to roll back, and will announce it this morning.

I fully agree with your reasoning, plus...

1.  As you say, "Weather could..." (and almost certainly WILL) "...be a no go for launch," so practically no chance of rushing to get launched before the storm arrives.

2.  Given that, the risks are much higher than 5%, if they don't start rollback by tomorrow at the latest.  The NHC "Tropical-Storm-Force Wind Speed Probabilities" graphic shows the Cape in the 5%-10% band at 108 hours (around launch time), but by 120 hours (2 am Wednesday) the Cape is on the line between 10%-20% and 20%-30%, so about a 20% probability.

3.  Looking at the track guidance models, which are in fair agreement, I would roughly extrapolate at least a 50% probability of tropical-storm-force winds by Thursday.

4.  None of the above is a certainty, of course.  But it isn't some miniscule chance, either.  The bundle of risk seems to me far too high for them to do anything but start rollback today.

5.  If I can come to that conclusion with forecasting resources available on the web, NASA has already gotten there with the skills available to them.

The stresses on the rocket from a rollback and another rollout are not insignificant, as we have been told.  Seems to me they pale in comparison to the embarrassment that would result from losing Artemis I to Hurricane Hermine.
a Civil Engineer, in an age of incivility...

Tags:
 

Advertisement NovaTech
Advertisement SkyTale Software GmbH
Advertisement Northrop Grumman
Advertisement
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0